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btrfs: remove redundant csum buffer in btrfs_io_bio

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The io_bio tracks checksums and has an inline buffer or an allocated
one. And there's a third member that points to the right one, but we
don't need to use an extra pointer for that. Let btrfs_io_bio::csum
point to the right buffer and check that the inline buffer is not
accidentally freed.

This shrinks struct btrfs_io_bio by 8 bytes.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
David Sterba 2018-11-22 17:16:46 +01:00
parent 600b6cf468
commit 31fecccbd7
2 changed files with 7 additions and 6 deletions
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12
fs/btrfs/file-item.c
View File

@ -144,7 +144,10 @@ int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
static void btrfs_io_bio_endio_readpage(struct btrfs_io_bio *bio, int err)
{
kfree(bio->csum_allocated);
if (bio->csum != bio->csum_inline) {
kfree(bio->csum);
bio->csum = NULL;
}
}
static blk_status_t __btrfs_lookup_bio_sums(struct inode *inode, struct bio *bio,
@ -175,13 +178,12 @@ static blk_status_t __btrfs_lookup_bio_sums(struct inode *inode, struct bio *bio
nblocks = bio->bi_iter.bi_size >> inode->i_sb->s_blocksize_bits;
if (!dst) {
if (nblocks * csum_size > BTRFS_BIO_INLINE_CSUM_SIZE) {
btrfs_bio->csum_allocated = kmalloc_array(nblocks,
csum_size, GFP_NOFS);
if (!btrfs_bio->csum_allocated) {
btrfs_bio->csum = kmalloc_array(nblocks, csum_size,
GFP_NOFS);
if (!btrfs_bio->csum) {
btrfs_free_path(path);
return BLK_STS_RESOURCE;
}
btrfs_bio->csum = btrfs_bio->csum_allocated;
btrfs_bio->end_io = btrfs_io_bio_endio_readpage;
} else {
btrfs_bio->csum = btrfs_bio->csum_inline;

1
fs/btrfs/volumes.h
View File

@ -274,7 +274,6 @@ struct btrfs_io_bio {
u64 logical;
u8 *csum;
u8 csum_inline[BTRFS_BIO_INLINE_CSUM_SIZE];
u8 *csum_allocated;
btrfs_io_bio_end_io_t *end_io;
struct bvec_iter iter;
/*